make mki18n.py wx-3.0 compatible and fix segmentation fault

$ python mki18n.py -m -v --moTarget=../locale --domain=Beremiz
No project directory given. Using current one: /home/beremiz/beremiz/i18n
Application domain used is: 'Beremiz'
Target directory for .mo files is: ../locale
../src/common/stdpbase.cpp(62): assert "traits" failed in Get(): create wxApp before calling this
Segmentation fault

                  <xsd:element name="Xenomai">
                    <xsd:complexType>
                      %(toolchain_gcc)s
                      <xsd:attribute name="XenoConfig" type="xsd:string" use="optional" default="xeno-config"/>
                    </xsd:complexType>
                  </xsd:element>